BIPHASIC MULTILAMELLAR LIPID VESICLES

Abstract: A biphasic multilamellar lipid vesicle comprising a plurality of spaced apart lipid bilayers that include a liposome-forming component and optionally a biologically active agent entrapped within the lipid bilayers. The lipid vesicle also comprises peripheral aqueous solution compartments formed between the lipid bilayers and a central lipophilic core compartment substantially at the center of the multilamellar lipid vesicle.

Description: TITLE OF THE INVENTION Biphasic multilamellar lipid vesicles BACKGROUND OF THE INVENTION Liposomes are microscopic vesicles composed of con- centric or single phospholipid bilayers which enclose aqueous phases. These vesicles can serve as drug carriers for hydrophobic as well as hydrophilic substances, includ¬ ing various drug molecules and peptides. Liposomes are prepared mainly from phospholipids of different headgroups and chain lengths, and cholesterol. Due to physicochemical similarities with cellular membranes, liposomes are biocom- patible, biodegradable and non-toxic vehicles for drug molecules. Liposomes are prime candidates for the systemic as well as topical delivery of drugs. Several studies showed that liposome encapsulation advantageously alters the phar acokinetic fate of the drug after topical application. The first experimental evidence that liposomes may pene¬ trate into the skin and deposit within the dermis was obtained recently by using a novel small particle-size electrondense marker (colloidal iron) , which can be effi¬ ciently encapsulated into liposomes of various sizes and compositions, and can be easily identified in cells and tissues by electron microscope. However, current liposome technology suffers from a number of important drawbacks that has prevented its wide¬ spread use in dermal applications and in systemic delivery. Hence, liposome formulations present consistency problems for skin applications that have so far been solved by either adding viscosity-increasing agents such as cellulose derivatives to the final liposome preparation or by using higher concentrations of phospholipids in the preparation of the liposomes. The addition of viscosity-increasing agents to the final liposome preparation usually dilutes the product but more importantly, these agents were shown to decrease the RECTIFIED SHEET (RULE 91) ISA EP release of encapsulated drug from the liposomes. Also, viscosity-increasing agents have a detrimental effect on the integrity of the liposomes. With regard to phospho¬ lipids, they are the main and also the most expensive liposome-forming ingredient. Their use as a viscosity- increasing agent is therefore not economically practical. Another problem with current liposome technology is the available methods for making them. Methods such as the solvent evaporation method are very difficult to use on a large scale. Furthermore, the solvent evaporation method requires the use of toxic organic solvents such as chloro¬ form for the dissolution of liposome-forming components. Ultimately, some of these toxic solvents are found in the final product. Also, not all biologically active sub- stances are soluble in these organic solvents. Impotence, the partial or complete inability of the male to perform the sexual act or to achieve orgasm, may be psychogenic and/or organic in nature. Initially, psycho- genie etiology was considered to account for 95 percent of cases of impotence but it is now apparent that organic factors are almost invariably involved in cases of impot¬ ence. Thus, impotence is best characterized as either of predominantly organic or predominantly psychogenic etiology. Impotence is a socially crippling disease. It de¬ tracts from the patient's self esteem and in some cases his ability to interact with others. Current therapy modes include psychotherapy, microsurgery (to restore compromised vascular supply) , implantation of penile prosthesis and pharmacotherapy. Numerous agents have been employed in the therapy of impotence. Hormonal manipulation, such as replacement androgen therapy, has been used. However, patients with organic impotence are rarely candidates for hormonal mani- pulation. Thus, this mode of therapy should be strictly limited to cases in which endocrine deficiencies are RECTIFIED SHEET (RULE 91) 1SA/EP established. Furthermore, in about 50 percent of patients with an endocrinopathy, a psychogenic etiology can be shown to be the predominant factor in erectile difficulties. Therefore, in the vast majority of impotent men, vascular and neurologic factors are the underlying causes. The most commonly used treatment for these patients is the implanta¬ tion of penile prostheses. The invasive nature of this technique, coupled with the increasing evidence of mechan¬ ical failure, surgical complications, or infection has again focused attention on the development of pharmaco¬ logical agents with a potential for improving the libido and quality of erections. Several agents have been tested e.g. bromocriptine, glyceryl trinitrate, zinc, oxytocin, yohimbine and nitroglycerin. Intracorporeal injection of vasoactive agents is now considered the treatment of choice for many patients with organic impotence (Kattan et. al., 1991) . Injection of papaverine, a smooth muscle relaxant, or a combination of papaverine and phentolamine (an a- adrenergic blocker) directly into the corpus cavernosum (either of the two erectile columns of the dorsu of the penis) has been shown to be an effective therapy in impot¬ ence. Recently, intercavernosal injections of prosta- glandin E_, (alprostadil) , a naturally occurring chemical derived from dihomo-gammalinolenic acid (20:3∞6) was dis¬ covered to also induce erection. Injection of prostaglandin E- results in vasodilation, with increased arterial inflow and decreased venous outflow by occlusion of draining venules, probably through relaxa- tion of corporal smooth muscle. Due to its potent relaxant effect on vascular smooth muscle, prostaglandin E- is used to maintain the patency of the ductus arteriosus in the neonate. This is the only currently approved (FDA) indica¬ tion for prostaglandin E 1 . The effect of prostaglandin E- on erectile dysfunction is known to be dose dependent. «— -f " 9 " Prostaglandin E- (PGE- ) , a potent relaxant of the vascular smooth muscle, has been shown to be effective and safe in the treatment of impotence by increasing arterial inflow through vasodilatation and decreasing venous outflow by the occlusion of draining venules due to relaxation of corporal smooth muscle. As opposed to other previously used drugs such as papaverine or phentolamine, PGE- is not as frequently associated with the common side effects e.g. priapism, plaques at the injection site and liver function abnormalities, therefore it is clinically more acceptable. PGE- is usually self-injected into the corpus cavernosum through the lateral aspect of the shaft of the penis. This type of administration, however, is associated with penile discomfort, pain at the injection site and the inconveni- ence of application prior to intercourse. Topical applica¬ tion of PGE- would be in ideal route of administration, however, the drug itself (without a delivery system) cannot penetrate the skin in adequate concentration and would be metabolized within the skin very quickly before reaching the underlying tissues. It is estimated that condylomata acuminata contributes to 1.3-1.4 million office visits per year in the United States, representing a 580% increase between 1966 and 1983 (Center for Disease Control, 1983) . Condylomata acuminata is caused by the human papillomavirus (HPV) and it is one of the most commonly diagnosed viral sexually transmitted diseases. More than 50 types of HPV has been categorized and new types are constantly being identified. Certain subsets of HPV (mostly type 16 and 18) has been shown to be associated with malignant tumors of the ano-genital tract, respiratory tract and the skin. Conventional therapy for genital warts has included podophyllin, cryotherapy, trichloroacetic acid, electrical cautery, laser ablation and conventional surgery, and has been directed primarily at visible lesions. Recurrences after therapy for HPV infections is very common, which RECTIFIED SHEET (RULE 91) ISA/EP could be due to incomplete eradication of the virus since the presence of residual virus in normal-appearing tissue has been demonstrated. Interferon has activity against papillomaviruses, and cure infected cells by eliminating extrachromosomal viral DNA. Systemic application (i.m. injection) of interferon alpha in patients with genital warts was shown to be fairly successful, however it is associated with various side effects such as fever, myalgias, headache, nausea, fatigue. Intralesional IFN treatment appears to be a more promising approach for visible lesions, but it is not suitable for latent or subclinical infections. Initially highly posi¬ tive results (90% complete response) were reported with topical natural leukocyte IFN. Vesterinen et al. reported colposcopic remission in five out of eight patients with vaginal flat condylomas treated with a potent topical IFN cream. However, in spite of the improvement of clinical appearance, the cytology remained positive in all cases and two responding patients had recurrences in two months. SUMMARY OF THE INVENTION The present invention relates to a multilamellar lipid vesicle, particularly to biphasic multilamellar lipid vesi¬ cles. The biphasic lipid vesicle comprises a plurality of spaced apart lipid bilayers comprising a liposome-forming component and optionally a biologically active agent (for the purpose of this specification "biologically active agent or compound" shall mean any agent that has a pharma¬ cological, pharmaceutical or cosmetic effect) entrapped within the bilayers. The lipid vesicle also comprises peripheral aqueous solution compartments formed between the lipid bilayers and a central lipophilic core compartment substantially at the center of the multilamellar lipid vesicle. Preferably, the lipid bilayers are formed from an anhydrous proliposome gel comprising the liposome-forming component in admixture with a pharmaceutically acceptable RECTIFIED SHEET (RULE 91) ISA EP hydrophilic solvent other than water. The liposome-forming component is usually selected from the group consisting of glycolipids, phospholipids, ceramides and mixtures thereof and optionally, a fatty substance such as cholesterol is added to enhance the strength of the lipid bilayers. Optionally, the lipid bilayers can further comprise at least one cutaneous or percutaneous penetration enhancer agent entrapped within the lipid bilayers or absorbed on the surface thereof. Preferred penetration enhancer agents include fatty acylated amino acids such as monolauroyl- lysine. Incorporation of lipophilic substances in the central core compartment of the multilamellar lipid vesicle is accomplished through a lipophilic substance-in-water emulsion in the form of a droplet which comprises on its surface a liposome-formation promoting agent adapted to stabilize the liposome-forming component and to promote formation of lipid vesicles around the droplet. The lipo¬ some-formation promoting agent is preferably a surfactant or a primary cationic emulsifier such as linoleamidopropyl PG-Dimonium chloride phosphate (PEFA) . Hence, oil droplets or solid/semisolid lipophilic ingredients can be encapsulated into liposomes. This encapsulation specifically includes coating the oil drop- lets or solid/semisolid lipophilic ingredients with a suitable surfactant followed by a reduction of the size of the droplets to below about 0.5 μM using a high pressure homogenizer. This procedure provides a milky solution which can be used in place of an aqueous phase in the formation of liposomes. Coated droplets are encapsulated into the central core compartment of the liposomes and are then surrounded by multiple bilayers. In this type of system, the end product can contain the targeted encapsu¬ lated drug in three different compartments within the liposome: lipid bilayers, the peripheral aqueous solution compartments and the central lipophilic core. RECTIFIED SHEET (RULE 91) ISA/EP Preferred lipophilic substances that can be incor¬ porated in the central core of the multilamellar lipid vesicles of the present invention include oils and solid or semisolid liphophilic consistency enhancers in which bio- logically active lipophilic compounds can be incorporated. Also within the scope of the present invention is a liposome composition comprising a population of biphasic multilamellar lipid vesicles, as described above. Also within the scope of the present invention is a process for the preparation of biphasic multilamellar lipid vesicles having a plurality of lipid bilayers. The process comprises forming a lipid phase melt by mixing a liposome- forming component and preferably a fatty substance adapted to enhance the strength of lipid bilayers with a pharma- ceutically acceptable hydrophilic solvent other than water and optionally a biologically active compound to produce an anhydrous proliposome gel in the form of a stable liposome- forming lipid phase melt. An lipophilic solution optional¬ ly comprising a biologically active compound is then added to the proliposome gel and the multilamellar lipid vesicles are recovered. Preferably, the lipophilic solution is a lipophilic substance-in-water emulsion in the form of a plurality of droplets comprising on their surface a liposome-formation promoting agent adapted to stabilize the liposome-forming component and to promote the formation of lipid vesicles around the droplets. This solution is prepared by dis¬ solving liposome-formation promoting agent in water and adding the lipophilic substance to the water. The lipo- philic substance preferably comprises at least one com¬ ponent selected from the group consisting of an oil and a solid or semisolid lipophilic consistency enhancer. Also within the scope of the present invention is a multilamellar lipid vesicle to be used particularly for topical applications. The lipid vesicle comprises a plurality of spaced apart lipid bilayers comprising a RECTIFIED SHEET (RULE 91) ISA/EP liposome-forming component preferably in admixture with a fatty substance adapted to enhance the strength of the bilayers and optionally a biologically active agent en¬ trapped within the bilayers. The lipid vesicle also comprises peripheral aqueous solution compartments formed between the lipid bilayers and a central aqueous core compartment substantially at the center of the multi¬ lamellar lipid vesicle. The peripheral compartments comprise at least traces of a pharmaceutically acceptable hydrophilic solvent other than water. The multilamellar lipid vesicles are devoid of traces of organic solvents, such as chloroform, which are usually employed in conven¬ tional liposome-forming techniques for dissolving the liposome-forming component. Preferably, the lipid bilayers are formed from an anhydrous proliposome gel comprising the liposome-forming component in admixture with the fatty acid substance and a pharmaceutically acceptable hydrophilic solvent other than water. The liposome-forming component is usually selected from the group consisting of glycolipids, ceramides, phos¬ pholipids and mixtures thereof and the fatty substance is usually cholesterol. Optionally, the lipid bilayers can further comprise at least one cutaneous or percutaneous penetration enhancer agent entrapped within the lipid bilayers or absorbed on the surface thereof. Preferred penetration enhancer agents include fatty acylated amino acids such as monolauroyl- lysine. Two of the multiple applications of the multilamellar lipid vesicles of the present invention reside in their use for the treatment of erectile dysfunctions and papilloma- virus infections. For the treatment of erectile dysfunc¬ tions, a prostaglandin, preferably PGE 1# is incorporated in the lipid bilayers. As for the treatment of papillomavirus infections, interferon alpha is incorporated in the lipid bilayers. RECTIFIED SHEET (RULE 91) ISA/EP Also within the scope of the present invention is a liposome composition comprising a population of multi¬ lamellar lipid vesicles, as described above. The multi¬ lamellar lipid vesicle population has a substantially uniform size distribution, preferably ranging between 0.1 and 10 μm, while being substantially devoid of aggregated or fused liposomes, and devoid of traces of organic solvents usually employed for dissolving lipid-forming components. Also within the scope of the present invention is a process for the preparation of multilamellar lipid vesicles having a plurality of lipid bilayers. The process com¬ prises forming a lipid phase melt by mixing a liposome- forming component preferably with a fatty substance adapted to enhance the strength of lipid bilayers, a pharmaceutic¬ ally acceptable hydrophilic solvent other than water and optionally a biologically active compound to produce an anhydrous proliposome gel in the form of a stable liposome- forming lipid phase melt. An aqueous solution optionally comprising a biologically active compound is then added to the proliposome gel and the multilamellar lipid vesicles are recovered. Also within the scope of the present invention is a composition for preparing multilamellar lipid vesicles having a plurality of lipid bilayers. The composition comprises a liposome-forming component, preferably in admixture with a fatty acid substance adapted to enhance the strength of the lipid bilayers, and a pharmaceutically acceptable hydrophilic solvent other than water to produce an anhydrous proliposome gel in the form of a stable lipo¬ some-forming lipid phase melt. Also within the scope of the invention is a method for the treatment of erectile dysfunctions. This method com¬ prises topically administering to a patient in need thereof an effective amount of a liposome composition comprising a population of multilamellar lipid vesicles. The multi- RECTIFIED SHEET (RULE 91) ISA EP lamellar lipid vesicles comprise a plurality of spaced apart lipid bilayers comprising a liposome-forming com¬ ponent, preferably in admixture with a fatty substance adapted to enhance the strength of the lipid bilayers, and PGE- entrapped within the lipid bilayers. The multi¬ lamellar lipid vesicles also comprise peripheral aqueous solution compartments formed between the lipid bilayers and a central aqueous or lipophilic core compartment substan¬ tially at the center of the multilamellar lipid vesicle. The peripheral compartment comprise at least traces of a pharmaceutically acceptable hydrophilic solvent other than water. The multilamellar lipid vesicle population has a substantially uniform size distribution while being sub¬ stantially devoid of aggregated or fused liposomes and devoid of traces of organic solvents suitable for dis¬ solving the lipid bilayers, for the purpose of treating erectile dysfunctions. Also within the scope of the present invention is the use of a topical liposome composition for the application of PGE- in the treatment of erectile dysfunctions. The liposome composition comprises the multilamellar lipid vesicles or the biphasic multilamellar lipid vesicles described above. Also within the scope of the present invention is the use of the multilamellar lipid vesicles or the biphasic multilamellar lipid vesicles described above in the preparation of a topical medicament comprising PGE. for the treatment of erectile dysfunctions. The invention also relates to a method for the treatment of papilloma- virus infections. The method comprises topically admini- stering to a patient in need thereof an effective amount of a liposome composition comprising a population of multi¬ lamellar lipid vesicles. The multilamellar lipid vesicles comprises a plurality of spaced apart lipid bilayers comprising a liposome-forming component, preferably in admixture with a fatty substance adapted to enhance the strength of the lipid bilayers, and interferon alpha RECTIFIED SHEET (RULE 91) ISA/EP entrapped within the lipid bilayers. The multilamellar lipid vesicles comprise peripheral aqueous solution com¬ partments formed between the lipid bilayers and a central aqueous or lipophilic core compartment substantially at the center of the multilamellar lipid vesicle. The peripheral compartments comprise at least traces of a pharmaceutically acceptable hydrophilic solvent other than water. The multilamellar lipid vesicle population has a substantially uniform size distribution while being substantially devoid of aggregated or fused liposomes and devoid of traces of organic solvents suitable for dissolving said lipid bi¬ layers. Also within the scope of the present invention is the use of a topical liposome composition for the application of PGE- in the treatment of impotence. The liposome com¬ position comprises a population of multilamellar lipid vesicles of biphasic multilamellar lipid vesicles. Also within the scope of the present invention is the use of multilamellar lipid vesicles or biphasic multi- lamellar lipid vesicles in the preparation of a medicament for the treatment of papillomavirus infections. The multilamellar lipid vesicles developed in the con¬ text of the present invention have shown high encapsulation efficiency of hydrophilic, lipophilic and oil-like active ingredients. The simplicity of the method by which the vesicles are prepared allows production on a large scale. With the method of the present invention, a finished product which is not a liposomal intermediate can be pro¬ duced and then incorporated into another cream-based or gel matrix to make a final product. The term "biologically active agent" when used herein is intended to designate compounds having a medicinal activity as well as compounds used in the preparation of cosmetics. One of the decisive advantages of the method developed in the context of the present invention is the fact that it RECTIFIED SHEET HULE91) ISAEP does not make use of toxic organic solvents such as chloro¬ form or methanol. In fact, one of the important features of the present invention is the use of liposome-forming components such as phospholipids and other necessary exci- pients in the form of a "melt" system which is prepared using a pharmaceutically acceptable hydrophilic solvent such as propylene glycol. Propylene glycol is used as a plasticizer and an aid to prepare a uniform melt. The resulting liposomes are thus free of any trace of organic solvents. With the use of the process of the present invention, a more physically stable liposome composition is obtained. Hence, a more uniform liposome-size distribution is achieved while aggregation and fusion of liposomes is reduced to a minimum. Furthermore, the consistency of the final liposome composition is also substantially improved. It has also been demonstrated that encapsulation efficiency is higher or at least as good as the more conventional solvent evaporation method. It would also appear that encapsulation is more reproducible and this is indicated by smaller standard deviations. Other important features of the liposomal composition of the present invention include the possibility of encap¬ sulation and coencapsulation of a wide range of active ingredients with different physico-chemical properties. For example, lipid compounds which are not soluble in organic solvents can now be used for liposome construction. This type of product could not even be made with the tradi¬ tional solvent evaporation methods which involve the dis- solution of liposome ingredients in a mixture of chloroform and methanol. Furthermore, the multilamellar lipid vesicles develop¬ ed using the process of the present invention can be used to deliver oil droplets containing solubilized lipophilic drugs or oily plant extracts. The present invention also allows the encapsulation of lipophilic solid/semisolid con- RECTIFIED SHEET (RULE 91) ISA/EP sistency enhancers into the central core compartment of the multilamellar lipid vesicles. This provides enhanced viscosity for the final product and eliminates the require¬ ments to add viscosity-increasing agents to the final lipo- some preparation. Also, the formulation of liposomal IFN has contributed to the development of an effective form of topical inter¬ feron, and offer the advantage of treating latent HPV infections as well as visible genital warts and could be administered by the patients at home without the need for multiple painful local or i.m. injections. The present invention will be more readily illustrated by referring to the following description. IN THE DRAWINGS Figure la is a photograph of multilamellar liposomes prepared with solvent evaporation method. Figure lb is a photograph of multilamellar liposomes prepared by the present inventor using "anhydrous plastic proliposome-gel" ('melt') method. Figure 2 is a schematic side sectional view of a MLV with a central aqueous core. Figure 3 is a schematic side sectional view of a MLV with a central lipophilic core comprising an oil droplet. Figure 4 is a schematic side sectional view of a MLV with a central lipophilic core comprising a semisolid con¬ sistency enhancer. DETAILED DESCRIPTION OF THE INVENTION The invention relates to liposomal compositions for oral and topical use. The compositions of the present invention are particularly suitable for the dermal and transdermal delivery of biologically active compounds such as prostaglandins and proteins. The liposome compositions of the present invention can be used for the topical administration of biologically active compounds to hairy or hairless areas of the skin. They can also be used in mucus membranes for nasal, buccal, ocular, otic, vaginal and RECTIFIED SHEET (RULE 91) ISA EP urethral administration. The liposome compositions can also be used for localized (intradermal and intramucosal) or systemic (transdermal or transmucosal) delivery as well as in subcutaneous or intracutaneous injection for slow release depot in or beneath the skin. Each aspect of the present invention will be described in detail and followed by specific examples of applications in the treatment of erectile dysfunction and papillomavirus infections. The first section will discuss the preparation of multilamellar lipid vesicles with a central aqueous core. This will be followed by a second section describing the preparation of the biphasic multilamellar lipid vesicles having incorporated therein a central lipophilic core. A. Preparation of multilamellar vesicles with a central aqueous core compartment 1° Formation of an anhydrous plastic proliposome gel The anhydrous proliposome gel is an important inter¬ mediate in the formation of the multilamellar vesicles of the present invention. This gel is prepared using a mixing technique that is used frequently in emulsion technology. A liposome-forming component and other necessary excipients are melted with a pharmaceutically acceptable hydrophilic solvent such as propylene glycol which would normally be part of the formula's aqueous phase. In addi¬ tion, the following (or other similar) extracts can be used in place of the propylene glycol for mixing with the lipo¬ some forming component to produce an anhydrous proliposome gel: lavender, sage, rosemary, roman chamomile, carrot, myrrh, pot marigold, elder, arnica, eucalyptus, witch hazel, devil's claw, meadow sweet, willow, silver birch, rose hips, German chamomile, horse chestnut, cypress, incense, benjamine, thyme, gingko biloba and yarrow. The term "liposome-forming component", when used herein, is intended to designate any substance that is used as a major component in the preparation of lipid bilayers. RECTIFIED SHEET (RULE 91) ISA/EP Typical liposome-forming components include glycolipids, lecithins, phospholipids, ceramides or mixtures thereof which are used as a primary ingredient in the formation of the lipid bilayer. However, other natural and synthetic compounds having the required amphipatic character can be used to form liposomes. The choice of the appropriate materials is within the knowledge of the person skilled in the art. Examples include phosphatidylethanolamine, lyso- lecithin, lysophosphatidylethanolamine, phosphatidylserine, phosphatidylinositol, sphingomyelin, cardiolipin, phos- phatidic acid and the cerebrosides, ether lipids and phytanols. The liposomal formulations of the present invention preferably contain saturated and/or unsaturated phospho- lipids, more preferably phosphatidylcholine, lysophospha- tidylcholine, phosphatidylserine, phosphatidylethanolamine, glycolipids and ceramides. The phospholipids are prefer¬ ably in combination with a penetration enhancing agent such as monolauroyllysine or methyl salicylate to achieve pre- dominantly transdermal delivery potential. With regard to the term "fatty substance", it is intended to designate any substance that is used as a - secondary agent to form the lipid bilayers. This secondary agent is used to enhance the strength of the lipid bilayers formed from the appropriate liposome-forming components. Examples of useful fatty substances include steroids such as cholesterol, corprostanol, cholestanol and cholestane and saturated long chain fatty acids such as stearic acid to improve physical stability and appearance of the product. As for the biologically active agent that can be en¬ trapped within the peripheral aqueous solution compartments or within the lipid bilayers, such compound includes, but is not limited to, nucleic acids, polynucleotides, anti- bacterial compounds, antiviral compounds, antifungal com¬ pounds, anti-parasitic compounds, tumoricidal compounds, RECTIFIED SHEET (RULE 91) ISA/EP proteins, toxins, enzymes, hormones, neurotransmitters, glycoproteins, immunoglobulins, immunomodulators, dyes, radiolabels, radio-opaque compounds, fluorescent compounds, polysaccharides, cell receptor binding molecules, anti- inflammatories, antiglaucomic agents, mydriatic compounds, local anesthetic, nucleoside analogues, etc. The hydrophilic solvent is used as a plasticizer of the liposome-forming component and an aid to prepare a uniform melt. The hydrophilic solvent is preferably non- toxic. Examples of hydrophilic solvents include but are not restricted to propylene glycol, glycerol, polyethylene glycol having a molecular weight ranging between 300 and 8000 and ethanol. The resulting melt can be described as being an anhydrous plastic proliposome gel. This anhydrous plastic proliposome gel contains all the lipid phase ingredients and can be prepared and stored in advance in large quantities. It is a semisolid material with a homo¬ genous consistency. 2° Formation of the multilamellar lipid vesicles Once the anhydrous plastic proliposome gel has been formed, the hydrophilic ingredients which are to form the liposomal composition, such as penetration enhancers, pre¬ servatives and the like, are prepared separately as an aqueous solution which is added to the lipid phase melt previously heated to the appropriate melting temperature that can range from 40°C to 80°C and vigorously mixed by any given technique which allows the achievement of the desired product size. Examples of mixing techniques include vor- texing or propeller mixing. At this stage, it is also possible to incorporate solid biologically active agents that will be entrapped within the lipid bilayers. This procedure is suitable for the preparation of various amounts of topical liposomal product. If vortex mixing is used as the agitation, up to about 20 g of the product can be prepared. If a laboratory scale propeller mixer is used, up to about 2000 g of the product can be RECTIFIED SHEET (RULE 91) ISA/EP made. This formulation procedure can also be adapted for large scale manufacturing. Hence, the propeller mixing technique can be directly scaled up by geometrically in¬ creasing the size of the vessel and the diameter of the propeller mixer. However, as the vessel size increases, the preferred set up would be a combination mixer i.e. a high intensity mixer with propeller mixer and a scraped surface agitator. The aqueous phase is pumped from tank A to tank B containing the anhydrous plastic proliposome gel at the required temperature and mixed. This procedure is suitable for the production of any topical liposomal product on a large scale. Liposomal compositions can be prepared with the multilamellar lipid vesicles of the present invention by using appropriate pharmaceutical additives. For example, it might be required to add viscosity increasing agents to the final liposome preparation. The addition of other pharmaceutically acceptable compounds is within the purview of the person skilled in the art. 3° Characteristics of the final multilamellar lipid vesicle product A schematic representation of a multilamellar lipid vesicle prepared in accordance with the process described above is shown at Figure 2. The multilamellar lipid vesicle, generally designated by reference numeral 2, is made of a series of spaced apart lipid bilayers 4, 6 and 8 which define a series of peripheral aqueous solution com¬ partments 3 and 5. The smallest lipid bilayer 7 defines in its center a central aqueous core compartment 9. In order to demonstrate the difference in properties observed in the liposome population produced in accordance with the method of the present invention, comparative tests were conducted between two liposome compositions prepared from the same ingredients but using either the solvent evaporation method or the anhydrous plastic proliposome gel method of the present invention. Figure la is a photograph RECTIFIED SHEET ( RULE 91) ISA/EP of the liposome population prepared using the solvent evaporation method and Figure lb is a photograph of the liposome population prepared using the anhydrous plastic proliposome gel method. As it can be seen by comparing Figures la and lb, the liposome population obtained using the anhydrous plastic proliposome gel method has a liposome size distribution which is substantially more uniform than the liposome population obtained using the solvent evapora¬ tion method. Also, minimal amounts of aggregated or fused liposomes are formed when using the anhydrous plastic pro¬ liposome gel method whereas large aggregates can be observ¬ ed in the liposome population obtained using the solvent evaporation method. Table 1 summarizes the physical properties of the liposome formulations shown in Figures la and lb. TABLE 1 Comparison of two identical formulas prepared by: a) solvent evaporation method (Formula #1) b) "anhydrous plastic proliposome-gel" ("melt') method (Formula #2) Formula no. Organoleptic properties Microscopy1/liposome size distribution 1 (Fig. la) white cream, homogeneous MLV, l-30μm, aggregation, fusion 2 (Fig. lb) white cream, homogeneous MLV, l-10μm, even distribution of lipo¬ somes, no fusion or aggregation Also, it has been demonstrated that the encapsulation efficiency of proteins into liposomes is higher or at least as good as the encapsulation efficiency using the solvent evaporation method without the drawback of traces of toxic solvents such as chloroform that are observed with the solvent evaporation method. Furthermore, it is important to mention that encapsulation seems to be more reproducible when using the anhydrous plastic proliposome gel method which presents a much smaller standard deviation than the RECTIFIED SHEET (HULE 91) ISA/EP solvent evaporation method. The results are summarized in Table 2. TABLE 2 Encapsulation efficiency of interferon alpha into liposomes B. Preparation of biphasic multilamellar lipid vesicles with a central lipophilic core compartment 1° Formation of the anhydrous plastic proliposome gel The procedure used to form the anhydrous plastic proliposome gel is the same as the procedure described previously. As mentioned before, this gel contains all the lipid phase ingredients used to form the lipid bilayers of the multilamellar lipid vesicle. It can be prepared and stored in advance in large quantities. 2° Formation of the central lipophilic core compartment The central lipophilic core compartment is made from a lipophilic substance-in-water emulsion in the form of a droplet comprising on its surface a liposome-formation pro¬ moting agent adapted to stabilize the liposome-forming com¬ ponent and to promote the formation of lipid vesicles around the droplet. The term "lipophilic substance", when used herein, is intended to designate oils or solid/semisolid lipophilic consistency enhancers which can be encapsulated into lipo¬ somes. Examples of oils which have successfully been encapsulated into liposomes include: olive oil, macadamia nut oil, rice bran oil, pumpkin seed oil, apricot kernel oil, hazelnut oil, rose hip seed oil, borage oil, tea tree oil, rocou oil, camellia oil, sweet almond oil, safflower oil, St. John's wort oil, lipodermol, pistachio nut oil, IECTIFIED SHEET (RULE 91) RL- - I ICSAΔ//EPP chia oil, kiwi seed oil, lesquerella oil, tiare oil, grape- seed oil, peanut oil, babassu oil, avocado oil, squalene, evening primrose oil, blackcurrent oil, pentaerythritol tetracaprylate/caprate, pentaerythritol tetraisostearate, cetearyl octanoate and canola oil, jojoba oil, peanut oil, rice bran oil, cottonseed oil, sunflower oil, corn oil, walnut oil, avocado oil, peru balsam, clove oil and eugenol. Plant extracts based on oil have also been successfully incorporated into liposomes such as from comfrey, German chamomile, cola nut, pot marigold, silver birch, cola nut, gingko biloga, witch hazel, willow, guarana, arnica, horse chestnut, eucalyptus, meadow sweet, rosemary, phyt'Iod, coffee, mate, tea and ivy. With regard to solid/semisolid lipophilic consistency enhancer ingredi- ents, they can be selected from waxes, fatty alcohols, fatty acid esters, glyceryl stearate, petrolatum or combin¬ ations thereof. Specific examples of preferred consistency enhancers include beeswax, glyceryl tribehenate, glyceryl stearate, stearyl heptanoate, cetearyl palmitate, cetyl alcohols, stearyl alcohol, myristyl myristate, behenyl erucate and cetyl palmitate. The term "liposome-formation promoting agent" when used herein is intended to designate compounds that can be used to stabilize the liposome-forming component and pro- mote the formation of lipid vesicles around the droplets. The obvious choice is surfactants. The surfactant used to coat the oil droplet or the solid/semisolid lipophilic con¬ sistency enhancer ingredients is important for the success¬ ful encapsulation of a lipophilic core into multilamellar lipid vesicles. About 30 different types of surfactants were screened and one family of surfactant gave the most acceptable results. This type of surfactant is a primary cationic emulsifier. The most preferred surfactant is linoleamidopropyl PG-Dimoniu chloride phosphate. It is considered to be a synthetic phospholipid complex. This surfactant is commercially available from Mona Industries RECTIFIED SHEET (RULE 91) ISA/EP Inc., Patterson New Jersey under the name "phospholipid EFA" . The other two members of this family, phospholipid SV or phospholipid PTC, are also acceptable but phospho¬ lipid EFA is preferred. Nonionic or amphoteric surfactants can also be used, such as naturally derived emulsifiers: PEG-60 almond glycerides, avocado oil diethanolamine, ethoxylated jojoba oil (PEG-40 Jojoba acid and PEG-40 Jojoba alcohol); polyoxyethylene derivatives: polyoxy- ethylene (20) sorbitan monooleate, polyoxyethylene (20) sorbitan monostearate; lanolin derivatives: polychol 20 (Laneth 20) , polychol 40 (laneth 40) ; neutral phosphate esters: PPG-cetyl ether phosphate, DEA oleth-3 phosphate. It is also possible to use anionic surfactants such as acylglutamates: TEA-cocoyl glutamate, sodium lauroyl gluta- mate, sodium hydrogenated tallow glutamate and sodium cocoyl glutamate. When preparing the lipophilic substance-in-water emulsion, the hydrophilic ingredients are all incorporated in the water phase of the emulsion. The surfactant is dissolved in water and any other ingredient of hydrophilic character is added. Once the water phase of the emulsion has been prepared, the oil and/or solid/semisolid lipo¬ philic ingredients are added to the water in a homogenizer for a period of time ranging from 5 to 30 minutes to obtain relatively small droplet size. Preferred droplet size ranges from 0.1 μm to 1 μirt. The lipid phase melt is then heated and the lipophilic substance-in-water emulsion is added and vigorously mixed by either vortexing or propeller mixing depending on the product size. The formulation procedure described above can be easily adopted for large scale manufacturing. The pro¬ peller mixing approach can be directly scaled up by geo¬ metrically increasing the size of the vessel and the diameter of the propeller mixer. However, as the vessel size increases, the preferred set up would be a combination mixer such as a high intensity mixer with propeller mixer RECTIFIED SHEET (RULE 91) ISA/EP and a scraped surface agitator. In a large scale opera¬ tion, the lipophilic substance-in-water emulsion is pumped from a first tank into a second tank containing the anhy¬ drous plastic proliposome gel at the required temperature and mixed. The types of compounds which can be encapsulat¬ ed into biphasic MLV include, but are not restricted to, prostaglandins, local anesthetic agents, proteins and pep- tides, antiviral agents, vitamins, antiinflammatory agents, antifungal agents, corticosteroids, plant extracts and amino acids. Specific examples include PGE-. , tetracaine, lidocaine, etidocaine, interferon alpha, interferon gamma, adenine-β-D-arabinofuranoside (Ara-A) , 5-methoxymethyl-2 '- deoxyuridine (MMUdR) , vitamin A, vitamin C, vitamin E, provitamin B-., azulene, allantoin, alpha-bisabolol and L- carnitine. 3° Characteristics of the biphasic multilamellar lipid vesicles having a central lipophilic core With this type of multilamellar lipid vesicles, the encapsulation and coencapsulation of active ingredients with different physical chemical properties, either hydro¬ philic or lipophilic, is possible. Figures 3 and 4 provide schematic figures of multilamellar lipid vesicle structures having a central lipophilic core compartment. As it can be seen in Figure 3, the multilamellar vesicle, generally designated by reference numeral 10, comprises a series of liposome bilayers 12, 14 and 16 spaced apart to define a series of peripheral aqueous solution compartments 13 and 15. The lipid bilayer defining the smallest circle 18 forms an interior space 19 that constitutes the central core compartment. When an oil droplet is used, the sur¬ factant acts to coat the surface of the droplet and stabil¬ ize it for encapsulation by a lipid bilayer. Following this first encapsulation, the remaining layers, once encap¬ sulated, will form peripheral aqueous solution compart- ments. Hence, it is important that the size of the RECTIFIED SHEET (RULE 91) ISA/EP droplets be very small so as to be incorporated into the central core of the multilamellar lipid vesicle. Similarly, when using a solid/semisolid lipophilic consistency enhancer, a central lipophilic core compartment is formed as shown in Figure 4. In this figure, the multi¬ lamellar vesicle, generally designated by reference numeral 20, comprises a plurality of liposome bilayers 22, 24 and 26 between which peripheral aqueous solution compartments 21 and 23 are formed. The lipid bilayer 28 having the smallest circumference, forms the central lipophilic core compartment 30. Central lipophilic core compartment 30 contains solid or semisolid consistency enhancers that are entrapped within the multilamellar lipid vesicle in the same manner as described before, that is through the use of a suitable surfactant. With the multilamellar lipid vesicle of the present invention, oil droplets containing solubilized lipophilic biologically active compounds or oily plant extracts can be delivered through liposome encapsulation. Furthermore, the possibility of multicompartment encapsulation provides drug release over extended periods of time. Also, encapsulation of lipophilic solid/semisolid consistency enhancers into the central lipophilic core compartment provides enhanced viscosity to the final liposome composition. In this case, the addition of viscosity-increasing agents in the final liposome preparation can be avoided. Overall, the preparation of multilamellar lipid vesicles with a central lipophilic core component provides a physically stable, uniform liposome composition. The composition has a viscosity that is suitable for topical administration and can be easily manufactured on a large scale. RECTIFIED SHEET (RULE 91) ISA/EP DESCRIPTION OF PREFERRED EMBODIMENTS A. Encapsulation of prostaglandins and prostaglandin analogs into multilamellar lipid vesicles Liposome encapsulated prostaglandins and prostaglandin analogs can provide benefit in a number of treatment areas. The following table summarizes the utility of liposome en¬ capsulated prostaglandins. The advantage of liposomal delivery of these prostaglandins is the more efficient, localized and targeted delivery to the desired tissues i.e. the skin, mucus membranes and surrounding tissues. The liposome system can be designed to provide a slow release depot at the target site within the skin or mucus membrane or localize the drug in the eye through bioadhesion and slow release or promote transdermal flux of the encapsulat¬ ed drug. Al. Encapsulation of PGE.. into multilamellar lipid vesicles for the preparation of liposome composition used in the treatment of erectile dysfunctions In order to overcome the problems associated with the administration of PGE- by injection, a new dosage form was developed which can be applied topically. PGE- is incor¬ porated into liposomes using the method of the present invention. This promotes its penetration through the skin of a penis and delivers a clinically useful concentration of drug into the corpus cavernosum. Liposome encapsulation RECTIFIED SHEET (RULE 91) ISA/EP enhances the penetration of the encapsulated PGE- through the penile skin and at the same time protects the drug within the skin from premature metabolism before reaching the target site. These properties make liposomes a suit- able delivery system for PGE- in the treatment of impot¬ ence. PGE.. is a lipid-soluble drug. Therefore, it can be encapsulated in the lipid bilayers and/or the central lipo¬ philic core of the liposomes. The encapsulation efficiency of PGE- into liposomes is manipulated by varying lipid composition, lipid/drug ratio, pH and the concentration of other excipients. Specific liposome compatible penetration enhancers/release agents are employed in designing an opti¬ mal liposomal PGE., preparation for dermal or transdermal delivery. 1° Encapsulation of PGE- in multilamellar lipid vesicles with a central aqueous core compartment Multilamellar liposomes were prepared as follows: the lipid ingredients and the hydrophilic solvent propylene glycol were weighed into a glass vial or beaker and melted at 65 - 75°C by intermittent heating on a hot water bath. The hydrophilic ingredients were prepared separately as an aqueous solution. The lipid phase melt and aqueous phase solution were stored at -20°C and at 4°C respectively, until required. PGE- was stored as an ethanolic solution at -20°C. Prior to liposome formulation, the ethanol solvent was evaporated under nitrogen; the lipid phase melt was added to the solid PGE- and mixed thoroughly by inter¬ mittent warming and vortex agitation. The lipid phase melt containing PGE- and the aqueous phase were then heated to 55°C and the aqueous phase was added to the lipid phase melt and vigorously mixed by vortexing or propeller mixing depending on the product size. The composition and encapsulation efficiency of selected liposomal PGE- formulations developed for trans¬ dermal delivery (Formulas #1, #2, #5 and #6-0.1%) and for NOTIFIED SHEET (RULE 91) ISA EP dermal delivery (Formula #3 and 4) are shown in Table 3. The liposomal formulations for the transdermal delivery of PGE- contain saturated and/or unsaturated phospholipids, especially phosphatidylcholine, lysophosphatidylcholine, phosphatidylserine, phosphatidylethanolamine, glycolipids. The liposomes also contain cholesterol, saturated long chain fatty acids (e.g. stearic acid) to improve physical stability and appearance of the product. The phospholipids are in combination with a penetration enhancing agent such as monolauroyllysine and/or methyl salicylate to achieve predominantly transdermal delivery potential. The liposomal formulations for the dermal delivery of PGE- can contain saturated and/or unsaturated phospho¬ lipids, especially phosphatidylcholine, lysophosphatidyl- choline, phosphatidylserine, phosphatidylethanolamine, glycolipids and ceramides. The liposomes may also contain cholesterol. To achieve predominantly dermal delivery cutaneous release agents such as unsaturated fatty acids (oleic acid) or short chain fatty acids (lauric acid) is added. TABLE 3 Liposomal PGE. formulas FORMULA # 1 Phospholipon 9OH 15% Cholesterol 2% Ascorbyl Palmitate 0.05% Phospholipon 80 1% Prostaglandin E 1 0.05% Propylene Glycol 7% Aqueous Phase F .s. Encapsulation Efficiency: 16% FORMULA #2 Phospholipon 9OH 15% Cholesterol 1.5% Ascorbyl Palmitate 0.05% RECTIFIED SHEET (RULE 91) ISA/EP Propylene glycol 7% Monolauroyllysine 1% Glycerol 5% Stearic Acid 0.5% Centrolex P 0.3% Prostaglandin E- 0.05% Aqueous Phase 16 q.s. Encapsulation Efficiency: 81% FORMULA # 3 Phospholipon 90H 15% Cholesterol 1.5% Ascorbyl Palmitate 0.05% Propylene glycol 7% Monolauroyllysine 1% Glycerol 5% Laurie Acid 0.5% Centrolex P 0.3% Prostaglandin E- 0.05% Aqueous Phase 16 q.s. Encapsulation Efficiency: 76% FORMULA # 4 Phospholipon 90H 15% Cholesterol 1.5% Ascorbyl Palmitate 0.05% Propylene glycol 7% Monolauroyllysine 1% Glycerol 5% Oleic Acid 1% Centrolex P 0.3% Prostaglandin E χ 0.05% Aqueous Phase 16 q.s. Encapsulation Efficiency: 67% REC T,F«ED SHECT (RULE 91) ISA/fcP FORMULA # 5 Phospholipon 90H 15% Cholesterol 1.5% Ascorbyl Palmitate 0.05% Propylene glycol 7% Monolauroyllysine 1% Glycerol 5% Stearic Acid 0.5% Centrolex P 0.3% Methylsalicylate 2% Prostaglandin E- 0.05% Aqueous Phase 16 q.s. Encapsulation Efficiency: 33% FORMULA # 6 - 0.1 Phospholipon 90H 15% Cholesterol 1.5% Ascorbyl Palmitate 0.05% Propylene glycol 7% Monolauroyllysine 1% Glycerol 5% Stearic Acid 0.5% Centrolex P 0.3% Methylsalicylate 2% Prostaglandin E- 0.1% Aqueous Phase 16 q.s. FORMULA # 7 Phospholipon 90H 15% Cholesterol 1.5% Ascorbyl palmitate 0.05% Propylene glycol 7.0% Monolauroyllysine 1.0% Glycerol 5.0% Stearic acid 0.5% Centrolex P 0.3% RECTIFIED SHEET (RULE 91) ISAEP Prostaglandin E- 0.05% Calcium thioglycolate 1.0% Aqueous phase 16 q.s. to 100% CONVENTIONAL (NON-LIPOSOMAL) FORMULA Prostaglandin E- 0.05% Dermabase q.s. 2. In vitro testing of percutaneous absorption of PGE- The rate of diffusion of PGE- from the liposome prep¬ arations across full thickness adult foreskin from circum¬ cision surgery was investigated using Teflon® Flow-Thru Diffusion Cells (Crown Glass Co. Inc. Somerville, N.J.) 2 which have a surface area for diffusion of 0.32 cm . The diffusion cells are designed such that fluid may be contin¬ uously pumped through them in order to maintain sink conditions. A phosphate buffer (7.5 M Na-HPO,, 141.2 mM NaCl) isotonic with body fluids and having a pH of 7.2 was used as the perfusion fluid. The diffusion cells were mounted in a PosiBloc T ' M Diffusion Cell Heater (Crown Glass Co. Inc., Somerville, N.J.) maintained at 32°C by a circulating water bath. The flow rate was 3 mL per hour. Each experiment was conducted for a period of 24 hours continuously. Liposome prepara- tion (20 mg) containing 10 μg PGE- and 3H-prostaglandm E- as tracer, was applied to each cell at the beginning of each experiment. This amount is estimated to be roughly equivalent to the dose per unit surface area of the RECTIFIED SHEET (RULE 91) A/EP preparation (1.5g) that was applied on the shaft of the penis in the clinical trials. At least three replicates of each experiment were performed. The quantity of PGE- in each fraction was determined by liquid scintillation counting. Skin penetration parameters were calculated from the steady state part of the cumulative flux plots as follows: a) Permeability Coefficient, P=J/ΔC where J=steady state slope and ΔC=concentration of PGE- in the donor chamber 2 b) Diffusion Coefficient, D=h /6L where h=mean thickness of foreskin specimen---*lmm and L=lag time in seconds. For the treatment of impotence there is a requirement to deliver 5-40 μg PGE- (the equivalent amount delivered during intracavernous injection) transdermally. This amount should be delivered within short period (ideally within lh) to be practically useful. The data obtained shows that PGE- can be delivered transdermally by appro- priate liposomal formulas. Table 4 shows the percutaneously delivered PGE- in vitro through human foreskin. Formulas #1, 2, 5 and 6- 0.1% illustrate the formulation approach to develop a transdermal product. TABLE 4 Percutaneous absorption of PGE. from liposomal formulations in 24 hours RECTIFIED SHEET (RULE 91) ISA/EP The initial drug concentration used in these formulas was 0.05%. Effective drug concentration in these formulas can vary between 0.01-5%. As illustrated with formula #5 and 6-0.1%, increasing drug concentration to 0.1% doubled the amount of transdermally delivered PGE- . The percutaneous absorption parameters are shown in Table 5. The flux values obtained for the products correlated well with their in vivo efficacy assessed by doppler ultrasonography. The higher flux values indicate higher potency in the patients. Formulas #3 and 4 show low transdermal delivery potential. TABLE 5 I vitro skin penetration parameters Table 6 shows the extent of delivery of PGE., with the various formulas. Formulas #3 and 4 are examples for formulas to achieve predominantly cutaneous delivery. RECTIFIED SHEET (RULE 91) ISA/EP TABLE 6 CO * % of total applied The transdermal versus dermal delivery potential of these formulations is reflected in the T/D ratio (Table 7) calculated from the mean (μg) transdermally absorbed drug and the mean (μg) cutaneously (whole skin count) delivered PGE- amount. TABLE 7 Transdermal versus dermal delivery ratios for liposomal PGE- products 4. Physical stability of liposomal products Physical stability of the liposomal formulations was assessed by visual and microscopic evaluation immediately after preparation and at weekly intervals following storage at room temperature, or at 4°C. The liposomal formulas were physically stable even after prolonged storage at room temperature and at 4°C. The formulations were completely homogenous with no signs of phase separation macroscopically. Under the light microscope, numerous multilamellar liposomes of varying sizes and mostly spherical shape were seen. There was no increase in fusion or aggregation products (indicators of liposome instability) upon storage. 4. Stability of PGE- in liposomal formulations Stability of PGE- was analyzed by thin-layer chroma- tographic (TLC) and radiometric methods. 4.1. TLC Assay Degradation of PGE- was assessed by TLC analysis of the diffusion cell fractions and the liposomal PGE- formu- lation (after storage at 4°C for 2 weeks) . The aqueous RECTIFIED SHEET (RULE 91) fractions from diffusion cell experiments were pooled and freeze-dried. The PGE.. was extracted with methanol, filtered through a Millipore filter and concentrated prior to spotting. The liposomal PGE- formulation was diluted with either methanol or dioxane prior to spotting. The mobile phase used was Benzene:Dioxane:Acetic acid (20:20: Iv/v) while color reagent was Absolute Ethanol:4-Methoxy- benzaldehyde:Concentrated Sulphuric Acid (20:20:2v/v) . After the chromatographic run the plate was allowed to dry, sprayed with the color reagent, allowed to dry again for at least 15 minutes and heated in the oven at 85°C for 10 minutes for full color development. The PGE., spots appear¬ ed as dark brown spots, identical to a co-chromatographed PGE- standard. 4.2. Radiometric assay Semi-quantitative assay of the thin-layer chromato- grams was done by liquid scintillation counting of the PGE- spots and the rest of the chromatogram and expressing PGE- concentration as a percentage of total counts obtained in the chromatogram. PGE- was positively identified on thin-layer chromato- grams of the liposomal PGE.. formulation after storage for 2 weeks in the refrigerator. Based on visual examination of the intensity of color development and band width, little or no PGE- degradation appeared to have occurred. 5. Encapsulation efficiency and leakage studies Liposome encapsulation of PGE- is proposed to enhance its stability hence the greater the encapsulation effi¬ ciency, the more stable the drug will be in the formula- tion. The encapsulation efficiency of PGE- into liposomes was determined by liquid scintillation counting. Aliquots of the liposomal cream were diluted with the aqueous phase and centrifuged at 200,000 xg for 60 minutes. The super- natant was separated from the pellet (liposomes) and the weights recorded. Calculated amounts of the supernatant RECTIFIED SHEET (HULE 91) ISA EP and pellet were dissolved in scintillation cocktail and counted. The concentration of PGE- in each fraction were derived from the total activity (dpm) in each fraction. Encapsulation Efficiency=Concentration of PGE., in pellet/ (Concentration in pellet and supernatant) Encapsulation efficiency studies were repeated at weekly intervals for 2 weeks to determine leakage of encap¬ sulated drug from liposomal formulations stored either in the refrigerator or at room temperature. 6. Clinical evaluations The protocols for the human studies were accepted by the Ethics Committee on Human Experimentation at the University of Saskatchewan. Patients included in these studies were diagnosed as having impotence of primarily organic origin. This group of patients is the most difficult to treat and they usually require higher doses of PGE- . The rationale for using this "difficult" group is to decrease the possibility to obtain placebo responses. 6.1. Double blind crossover trial Six patients diagnosed as having impotence of predom¬ inantly organic etiology and shown to respond to intra- cavernous PGE- injection were enroled in the study after proper consent. A double blind, randomized, crossover design was employed to test a liposomal PGE- against a liposomal placebo, 1.5g of each cream was applied to the shaft of the penis at weekly intervals. Prior to this, a small amount was applied to a non-hairy part of the arm to test for adverse reactions. If none occurred within 60 minutes, the patient then proceeded with the actual test later in the day. The cream was washed off after 1 hour and prior to intercourse, if an erection was obtained. The patient was requested to note the onset, duration and quality of response as well as any side effect on the response sheets provided. RECTIFIED SHEET (RULE 91) ISA EP The study indicated that 5 out of 6 patients responded to the test preparation to various degrees (Response ranking > 1, Table 8) . Three patients responded with high scores (response ranking > 2) . Response to the placebo was practically zero. TABLE 8 Pilot clinical study using Formula # 6 (0.1%) in patients with organic impotence Response ranking 0 No effect whatsoever observed. 1 Slight effect i.e. slight enlargement of the penis. No erection. 2 Erection obtained but not sufficient for intercourse. 3 Good erection obtained. Intercourse attempt¬ ed but not satisfactory. 4 Good erection obtained. Satisfactory inter¬ course. 6.2 Doppler ultrasonoqraphy study Doppler ultrasonography was used to assess the degree of arterial dilatation and measure penile arterial blood flow following application of transdermal liposomal PGE- . Three liposomal PGE- preparations and a placebo control were tested. Test preparations were administered at no less than 2 week intervals. After initial sonographic examination to determine blood flow in the flaccid penis, the test preparation was applied on the shaft and glans RECTIFIED SHEET (RULE 91) ISA EP penis after which an occlusive wrapping was placed around the penis. The penile blood flow was monitored at 15 minute intervals for 1 hour. The doppler ultrasonography study on patients with predominantly organic impotence showed increased penile blood flow after topical liposomal PGE- application (Table 9) , Liposome formula #5 showed the greatest efficacy, with a peak flow of 32 cm/s in Patient #4. The control liposome #5 formulation (without PEG-) also exhibited an increase in penile blood flow. The #5 liposome preparation is equivalent to the #2 plus a penetration enhancing agent, methyl salicylate. It is likely that this penetration enhancer increases penile blood flow to a small degree by itself and is synergistic with liposomal PGE- . The in vitro percutaneous absorption data correlated very well with the doppler results. In vitro #5 liposomal PGE- gave the highest percutaneous flux followed by #2 and lastly, the #7 liposomal PGE- formula¬ tion. RECTIFIED SHEET (HULE 91) ISA/EP TABLE 9 Peak systemic flow velocity (cm/s) : deep cavernosal artery _D rπ C) 3! m α 3> x L rπ m 00 Ώ c: rΓΠ~ CD 0 No ultrasonographically detectable flow. MSC Methylsalicylate Other possible uses for topically applied liposomal PGE- include the preparation of transdermal formulations for the treatment of impotence as well as the preparation of dermal formulations for the treatment of various skin conditions such as atopic skin, psoriasis, peripheral vascular diseases, wound healing and ischaemic lesions. B. TOPICAL LIPOSOME-ENCAPSULATED INTERFERON ALPHA FOR THE TREATMENT OF GENITAL PAPILLOMAVIRUS INFECTIONS Methods Liposome preparation The method used in A. was also used to incorporate IFN alpha which is included in the aqueous phase which is used to hydrate the proliposome gel by mixing at a temperature not exceeding 40"C. In situ hybridization For the determination of the presence of HPV DNA (types 6 and 11, types 16 and 18, and types 31, 33, and 35) in paraffin-embedded tissue sections from biopsies of patients, ViraType TM in si.tu Human Papillomavirus Tissue Hybridization Kit (Life Technologies, Inc., Gaithersburg, MD) was used. Immunostaining Biopsy sections before and after treatment with liposomal IFN alpha were immunostained for the presence of absorbed IFN by using mouse anti-human IFN monoclonal antibody (Boehringer Mannheim Biochemica) and alkaline phosphatase labelled secondary antibody in the form of AS/AP TM universal Mouse Immunostaining Kit (BIO/CAN Scientific Inc., Mississauga, Ont.). Clinical study The first patient was a 30-year old female with a three- year history of recurrent genital HPV with cervical involvement (CIN I) . On examination prior to instituting topical IFN alpha (F#2) therapy, large confluent plaques and separate verrucous and filiform papules typical for condylomata acuminata were present on the labia ajora, RECτlFl ED SH^ (BULE 91) labia minora and upper thighs. Histopathology showed condyloma with mild intraepithelial atypia. VIRA-PAP was positive for HPV 6/11. In situ hybridization showed positivity for HPV 6/11, faint reactivity for HPV 31, 33 and 35, negative for HPV 16/18. Treatment protocol was as follows 3xl0 6 IU/week liposome encapsulated Intron A for 12 weeks, then lOxlO 6 IU/week for 6 weeks; lg twice a day externally, and lg once a day intravaginally. The second patient was a 23-year old male with a two-year history of genital HPV. On examination there were multiple flat flesh-colored papules scattered over the shaft, foreskin and glans of the penis. Almost all of the lesions were acetowhite after five minutes of acetic acid soaking. Histopathology showed acanthosis, koilocytes, inflammation. VIRA-PAP was positive for HPV 6/11, negative for HPV 16/18, 31,33 and 35. In situ hybridization was negative for 6/11; 16/18; 31, 33 and 35. Treatment protocol 3xl0 6 IU/week liposome encapsulated Intron A for 8 weeks, lg twice a day externally. Assessment in both cases was carried out by monitoring the size and number of lesions, histopathology and in situ hybridization. Results Cutaneous penetration of 125I-IFN The absorption of IFN from various liposomal formula- tions into human breast skin in vitro was investigated using iodinated IFN as a label. The range of concentration of IFN investigated was 20-80 MU/g preparation. The usual 2 applied dose was 0.1 g preparation/0.32 cm skin surface area in the diffusion cell, which corresponds to about 2 6-28 MU IFN per cm skin surface area depending on the concentration tested. The experiments utilized human breast skin from mammoplasty. The cutaneous penetration of IFN from various lipo¬ somal formulas containing 20 MU/g preparation are shown in Tables 10A and 10B. RECTIFIED SHEET (RULE 91) ISA'EP TABLE 10A Cutaneous absorption of 125I-IFN from liposomal formula¬ tions at 48 h steady state. The total amount of IFN in whole skin (all skin layers together) is presented Drug concentration in product: 20xl0 6 IU IFN/g product Dose/unit skin surface area: 6x10 6 IU IFN/cm 2 Skin used: 0716-92 1 Tracer: -25 D I-IFN Duration of experiment: 48 h The values represent the mean +. S.D. (n=4) RECTIFIED SHEET (RULE 91) ISA/EP TABLE 10B 125 Cutaneous absorption of I-IFN from liposomal formulations at 48 h steady state. The amount of IFN in the stratum cornβum and in the deeper layers of skin (viable epidermis and dermis) is presented. Drug concentration in product: 20x10 IU IFN/g product 6 2 Dose/unit skin surface area: 6x10 IU IFN/c Skin used: 0716-92 125 Tracer: I-IFN Duration of experiment: 48 h _u The values represent the mean ±S .O. (n=4) With the dosage regimen used in this study the applied 2 dose was around 6 MU/cm . The absorption of IFN from the various liposomal formulas was fairly similar, 2.00-3.56% of the total applied when the whole (unstripped skin was analyzed (Table 10A) . This corresponds to about 110,000- 2 218,000 IU IFN/cm skin. When the stripped skin was analyz¬ ed (Table 10B) , the difference in the rate of absorption into the deeper layers, i.e.* the viable epidermis and dermis, was noticeable. The amount of IFN delivered by Formulas #3, 5, 9, 10 and 11 was in the range of 72,000- 2 155,000 IU/cm . The control IFN solution at the same concentration and dose delivered approximately 77,000 IU IFN/cm 2 into 'whole' skin (1.23±0.38% of total applied) and 40,000 IU/cm 2 into the deeper layers of skin (0.64%±0.08 of total) . Similar results were obtained when more concentrat¬ ed solutions were used. Upon increasing the dose the amount of IFN absorbed also increased. Selected formulas with 40 MU/g were pre¬ pared and tested. In this case the applied dose was around 12 MU/cm 2 . F# 5-40, F#10-40 and F#ll-40 had the same lipid composition as before except the initial drug concentration was increased. The amount of absorbed IFN into skin reached about 0.5 MU/cm . Table 11 indicates that among these three preparations F#10-40 delivered the highest amount of IFN, close to 600, 2 000 IU/cm . After stripping the skin the level of IFN in the skin treated with Formula #10-40 was still close to 0.5 2 MU/cm . F#5-40 and F#ll-40 delivered somewhat lower quanti¬ ties of IFN into the deeper layers of the skin. RECnBED SHEEHRULEgi) ISA EP TABLE 11 Cutaneous absorption•of 125,IN-IFN from liposomal formulas containing 40MU/g IFN at 48 h steady state. The amount of IFN in whole skin (all skin layers together) and in the stratum corneum and in the deeper layers of skin are presented. Drug concentration in product: 40x10 IU IFN/g product Dose/unit skin surface area: 12xl0 6 IU IFN/cm 2 Skin used: 0716-92 _D Tracer: 125 I-IFN m o Duration of experiment: 48 h __ The values represent the mean +S.D. (n=4) in CO mm O With F#5 and F#10 the concentration of IFN was further increased to 80 MU/g to determine whether more drug can be delivered. Table 12 shows that F#10-80 delivered close 0.9 MU/cm 2 i.nto the skin. The vi.able epi.dermi.s and dermis con- 2 tained about 0.7 MU/cm . It is noteworthy that F#10 in general delivered a greater proportion of IFN into the deeper layers of the skin. This effect is more pronounced at 40 MU/g and at 80 MU/g product concentration (Tables 11 and 12) . Estimation of antiviral activity in skin treated with liposomal IFN alpha. RECTIFIED SHEET (RULE 91) P TABLE 12 Cutaneous absorption of 1 ~~ "2 ~~ 5,I-IFN from liposomal formulas containing 80MU/g IFN at 48 h steady state. The amount of IFN in whole skin (all skin layers together) and in the stratum corneum and in the deeper layers of skin are presented. Drug concentration in product: 80x10 IU IFN/g product Dose/unit skin surface area: 28xl0 6 IU IFN/cm 2 Skin used: 0716-92 Tracer: "1"2"5I.-IF cr~. CD Measuring cutaneous penetration by radioactivity is an efficient way of comparing several different formulations and calculate approximate levels of protein in the skin. However, this method cannot answer the question whether the protein absorbed is intact and active. In order to get a better understanding whether the radioactive label represents active protein, antiviral assays with the skin samples treated with liposomal IFN (20 MU/g) were carried out. These antiviral assays indicated that there was antiviral activity in the skin with each liposomal formula tested (Table 13) . The values obtained by antiviral assay were about ten times lower than the amount of IFN detectable in skin by the radioactive method for all formulas except F#10. In case of F#10 the antiviral activity corresponded well with the result from the radio¬ active experiments (compare Table 10A and Table 13) . TABLE 13 Estimation of antiviral activity in skin treated with liposomal IFN alpha in vitro Delivery of IFN alpha into surgically removed genital wart tissue Excised condyloma tissues were treated with low-dose liposomal IFN (F#10-80) to obtain preliminary information about the rate of drug delivery. The difficulty of in vitro experiments with wart tissues is the localization of ade¬ quate quantities of product on the surface of the lesions. RECTIFIED SHEET (RULE 91) The two dose regimens used (0.5 MU/lesion and 2 MU/lesion, approximately) was required to form a sufficiently thick layer of the product on the surface of the tissue and any additional amount would not be accommodated (it would fall off) . The results of these experiments are shown in Table 14. Seven excised condyloma lesions (average diameter 5 mm) were treated with an average of 0.5 MU dose of F#10-80. The amount of IFN delivered into the lesions was 34,400±18,100 IU (6.5% of the total amount applied). After determining the radioactivity in the 'whole' lesions (i.e. after thorough washing and blotting of the warts) , the outer layers were removed by tape stripping and the radio¬ activity remaining in the deeper layers was determined. The average amount of IFN in the deeper layer was 29,000±15,300 IU (5.5% of the total amount applied). Three condyloma lesions were used for the experiments with the higher dose (2 MU/lesion) treatment. The total amount of IFN delivered was 323,500±235,100 IU (14.8% of total) and the remaining radioactivity after stripping of the warts was 286,5001208,900 IU (9.5% of total). These experiments show potential for this formulation to deliver sufficient quantities of drug. However, by im¬ proving the experimental set up a better estimation of the delivery rate into wart tissue could be obtained. Some of the difficulties in these experiments are the availability of tissues of similar sizes, the application of the lipo¬ some cream to the lesions, the incubation set-up and the analysis of the tissues. Treatment of patients with liposome encapsulated IFN alpha (F#2) After several weeks of therapy of the female patient there was softening and thinning of the condyloma and also lightening of the hyperpigmentation. Three lesions removed under local anesthesia from the right upper thigh at tenth week of therapy were still resolved at the end of a 12-week RECTIFIED SHEET (RULE 91) ISA/EP course of liposomal interferon treatment and the area con¬ tinued to show no sign of recurrence seven weeks after removal. Colposcopy one month following discontinuation of liposomal interferon therapy showed no evidence of HPV involvement of the cervix. In case of the male patient, several lesions on the distal foreskin and glans resolved after two weeks of liposomal interferon twice a day. Multiple lesions remained after eight weeks of therapy, when the patient moved from the area and was lost to follow-up. The lesions which resolved within the first two weeks remained gone during the observation period. The pretreatment biopsy sections were not greatly different from the post-treatment sections, both showing acanthosis and papillomatosis, however koilocytic changes were less apparent in the post-treatment sections. In situ hybridization of tissue sections obtained by biopsy 18 week post-treatment of the female patient showed only a relatively weak, focal staining for HPV 6 and 11 in rare superficial cells as opposed to pretreatment, when the test showed numerous foci of positively staining nuclei within superficial layers of the epithelium. These latter results might indicate the elimination of HPV virus from the wart tissues. We conclude that liposomes are a suitable delivery system for IFN alpha and a dermatologically acceptable dosage form. Our preliminary clinical studies indicate the efficacy of topically applied liposome encapsulated IFN alpha in the treatment of genital HPV infections. B. Encapsulation of lipophilic solid or liquid active ingredient or consistency enhancer into the central core compartment of multilamellar lipid vesicles 1. Formulation procedure Multilamellar liposomes were prepared as follows: the lipid ingredients and the hydrophilic solvent propylene glycol are weighed into a glass vial or beaker and melted at 65 - 75°C by intermittent heating on a hot water bath. RECTIFIEDSHEET(RULE91) The hydrophilic ingredients and the oil droplets or solid/semisolid lipophilic ingredients are prepared separ¬ ately as an oil in water (o/w) emulsion. This intermediate product is called System A. System A contains a suitable surfactant, the key ingredient to coat the surface of the lipophilic droplets and stabilize them for encapsulation into liposomes. System A is prepared by dissolving the surfactant in distilled water and adding the oil and/or solid/semisolid lipophilic ingredients to the water at 60- 80°C in a homogenizer at 20-80 psig for 5-30 minutes to obtain small droplet size (<about 0.5 μm) . The lipid phase melt (which may or may not contain PGE.. ) is heated to 55°C and System A is added to the lipid phase melt and vigorously mixed by vortexing or propeller mixing depending on the product size. The following formulas have been prepared using this procedure. RECTIFIED SHEET (RULE 91) ISA/EP 2. Topical liposomal product with encapsulated oil droplet % (w/w) Phase A: Lipid Phase: Phospholipon 90H 5.0 Cholesterol 2.0 Stearic acid 1.0 System A: Part 1: Distilled water q.s. to 100 PEFA 4.0 Methylparaben 0.15 Propylparaben 0.05 Part 2: Olive oil 10.0 3. Topical liposomal product with encapsulated consistency enhancer 100 RECTIFIED SHEET (RULE 91) ISA/EP 4. Topical liposomal product with encapsulated oil droplet and consistenc enhancer 5. Topical liposomal product with encapsulated oily plant extract and consistenc enhancer RECTIFIED SHEET (RULE 91) ISA'EP 6. Topical liposomal product with encapsulated oil-soluble cosmetic active ingredient and consistency enhancer % (w/w) Phase A: Lipid phase: Phospholipon 9OH 5.0 Cholesterol 2.0 Stearic acid 1.0 System A: Part 1: Distilled water q.s. to 100 PEFA 4.0 Methylparaben 0.15 Propylparaben 0.05 Part 2: Vitamin E 10.0 Glyceryl stearate 1.0 Cetyl alcohol 0.6 Synthetic beeswax 0.28 7. Topical liposomal product with encapsulated lipophilic drug in multicompartments and with encapsulated oil droplet and consistenc enhancer RECTIFIED SHEET (RULE 91) P 8. Topical liposomal product with encapsulated lipophilic drug in multicompartments and with encapsulated oil droplet and consistenc enhancer 9. Topical liposomal product with encapsulated protein drug and with encapsulated oil droplet and consistency enhancer RECTIFIED SHEET (RULE 91) > ISA/EP Synthetic beeswax 0.28 10. Topical liposomal product with encapsulated antiviral drug combination with or without consistency enhancer Phase B: Aqueous phase F q.s. to 100 OR: 11. Topical liposomal product with encapsulated oil- soluble cosmetic active ingredients (vitamins) and consistency enhancer Phase A: Lipid phase: Phospholipon 90H 5.0 Cholesterol 2.0 Stearic acid 1.0 Ascorbyl palmitate 0.5 System A: Part 1: Distilled water q.s. to 100 PEFA 4.0 Methylparaben 0.15 Propylparaben 0.05 RECTIFIED SHEET (RULE 91) SSA'EP Part 2: Vitamin E 10.0 Vitamin A 2.0 Glyceryl stearate 1.0 Cetyl alcohol 0.6 Synthetic beeswax 0.28 12. Topical liposomal product with encapsulated oil and oil-soluble cosmetic active ingredient and consistency enhancer 13. Topical liposomal product with encapsulated oil and oil-soluble cosmetic active ingredient and consistency enhancer Phase A: Lipid phase: -TIRED SHEET (RULE 91) RE ISA/EP Part 2 : Alpha bisabolol 10.0 Rocou ami oil 3.0 Glyceryl stearate 1.0 Cetyl alcohol 0.6 Synthetic beeswax 0.28 14. Topical liposomal product with encapsulated protein dru and consistenc enhancer Part 2: Glyceryl stearate 1.0 Cetyl alcohol 0.6 When using compounds with acidic hydrophilic groups (phosphato, sulfato, etc.) the obtained SPLVs will be anionic; with basic groups such as amino, cationic lipo¬ somes will be obtained; and with polyethylenoxy or glycol groups neutral liposomes will be obtained. The size of SPLVs varies widely. The range extends from about lOOnm to about 10,000 nm (10 microns) and usually about 100 nm to about 1500 nm. Virtually any bioactive compound can be entrapped within a SPLV (entrapped is defined as entrapment within the aqueous compartment or within the membrane bilayer) . ) TlF\ED SHEET (RULE 91) REG 1 . I ISAΔ//PEPP TABLE 14 Treatment of excised condyloma tissues with low-dose topical liposomal IFN alpha (F#10-80) for 24 h. DOSE REGIMEN li 33 rπ o " 3. rπ α rπ_ m m rπ in oo _D c r~ m DOSE REGIMEN II: O TABLE 15 Formulation of topical liposomal IFN products. _X3 rπ m o (0 GO n > X m •' • r r π π _D C m O TABLE 15 (cont'd) 33 m O d -π rπ O > L m i " m m σ 33 C r m- CD TABLE 15 (cont'd) * encapsulation efficiency measurements are the average of 2-5 separate experiments COMPOUND A = dipalmitoyllysine COMPOUND B = monolauroyllysine c m CD TABLE 16 Properties of liposomes containing IFN alpha. t i c r ~ m D Stability of liposomes was evaluated after 1 month according to the following rating scale TABLE 16 (cont'd) Visual stability rating for disperse system products (S.A. Hanna, 1989) 9 No visual separation, completely homogeneous 8 No visual separation, virtually homogeneous 7 Very indistinct separation, no clear layer at bottom or top 6 Indistinct separation, no clear layer at bottom or top 5 Distinct separation, no clear layer at bottom or top 4 Homogeneous top or bottom layer, clear layer at bottom or top 3 Distinct separation, clear layer at bottom or top with no coalescence 2 Distinct separation with slight coalescence 1 Distinct separation with slight coalescence 0 Complete separation and complete coalescence en O

Claims: CLAIMS : 1. A biphasic multilamellar lipid vesicle comprising: a plurality of spaced apart lipid bilayers comprising a liposome-forming component and optionally a biologically active agent entrapped within said lipid bilayers; and peripheral aqueous solution compartments formed between said lipid bilayers; and a central lipophilic core compartment substantially at the center of said multilamellar lipid vesicle. 2. A biphasic multilamellar lipid vesicle according to claim 1, wherein said lipid bilayers further comprise a fatty substance adapted to enhance the strength of said lipid bilayers. 3. A biphasic multilamellar lipid vesicle according to claim 1, wherein said lipid bilayers are formed from an anhydrous proliposome gel comprising said liposome-forming component in admixture with a pharmaceutically acceptable hydrophilic solvent other than water. 4. A biphasic multilamellar lipid vesicle according to claim 3, wherein said anhydrous proliposome gel further comprises a fatty substance adapted to enhance the strength of said lipid bilayers. 5. A biphasic multilamellar lipid vesicle according to claim 1, wherein said liposome-forming component is select- ed from the group consisting of glycolipids, ceramides, phospholipids and mixtures thereof. 6. A biphasic multilamellar lipid vesicle according to claim 2, wherein said fatty substance is cholesterol. RECTIFIED SHEET (RULE 91) ISA/EP 7. A biphasic multilamellar lipid vesicle according to claim 1, wherein said lipid bilayers further comprise at least one cutaneous or percutaneous penetration enhancer agent entrapped within said lipid bilayers or absorbed on the surface thereof. 8. A biphasic multilamellar lipid vesicle according to claim 7, wherein said penetration enhancer agent is a fatty acylated amino acid. 9. A biphasic multilamellar lipid vesicle according to claim 7, wherein said penetration enhancer agent is mono¬ lauroyllysine or methyl salicylate. 10. A biphasic multilamellar lipid vesicle according to claim 1, wherein said lipid bilayers have incorporated therein a prostaglandin. 11. A biphasic multilamellar lipid vesicle according to claim 10, wherein said protaglandin is PGE1. 12. A biphasic multilamellar lipid vesicle according to claim 1, wherein said central lipophilic core compartment comprises a lipophilic substance in water emulsion in the form of at least one droplet comprising on its surface a liposome-formation promoting agent adapted to stabilize said liposome-forming component and to promote the forma¬ tion of lipid vesicles around said droplet. 13. A biphasic multilamellar lipid vesicle according to claim 12, wherein said liposome-formation promoting agent is a surfactant. 14. A biphasic multilamellar lipid vesicle as defined in claim 13, wherein said surfactant is a primary cationic emulsifier. BECTiBED SHEET (RULE 91) ISA EP 15. A biphasic multilamellar lipid vesicle according to claim 14, wherein said primary cationic emulsifier is selected from the group consisting of cocamidopropyl PG- dimonium chloride phosphate, stearamido PG-dimonium chlor- ide phosphate, linoleamidopropyl PG-Dimonium chloride phosphate. 16. A biphasic multilamellar lipid vesicle according to claim 12, wherein said lipophilic substance comprises at least one component selected from the group consisting of an oil and a solid or semisolid lipophilic consistency enhancer. 17. A biphasic multilamellar lipid vesicle according to claim 15, wherein said oil is selected from the group consisting of olive oil, macadamia nut oil, rice bran oil, pumpkin seed oil, apricot kernel oil, hazelnut oil, rose hip seed oil, borage oil, tea tree oil, rocou oil, camellia oil, sweet almond oil, safflower oil, St. John's wort oil, lipodermol, pistachio nut oil, chia oil, kiwi seed oil, lesquerella oil, tiare oil, grapeseed oil, peanut oil, babassu oil, avocado oil, squalene, evening primrose oil, blackcurrent oil, pentaerythritol tetracaprylate/caprate, pentaerythritol tetraisostearate, cetearyl octanoate, canola oil, jojoba oil, peanut oil, rice bran oil, cotton¬ seed oil, sunflower oil, corn oil, walnut oil, avocado oil, preu balsam, clove oil, eugenol, comfrey oily extract, german chamomile oily extract, cola nut oily extract, pot marigold oily extract, silver birch oily extract, cola nut oily extract, gingko biloba oily extract, witch hazel oily extract, willow oily extract, guarana oily extract, arnica oily extract, horse chestnut oily extract, eucalyptus oily extract, meadow sweet oily extract, rosemary oily extract, phyt'iod oily extract, coffee oily extract, mate oily extract, tea oily extract and ivy oily extract. RECTIFIED SHEET (RULE 91) ISA/EP 18. A biphasic multilamellar lipid vesicle according to claim 16, wherein said solid or semisolid lipophilic con¬ sistency enhancer is selected from the group consisting of fatty alcohols, waxes, fatty alcohol fatty acid esters, glyceride esters, white petroleum and combinations thereof. 19. A biphasic multilamellar lipid vesicle according to claim 18, wherein said solid or semisolid lipophilic con¬ sistency enhancer is selected from the group consisting of beeswax, cetyl alcohol, stearyl alcohol, myristyl yrist- ate, behensyl erucate, glyceryl stearate and cetyl palmitate. 20. A biphasic multilamellar lipid vesicle according to claim 16, wherein said lipophilic substance further com¬ prises a biologically active lipophilic compound. 21. A biphasic multilamellar lipid vesicle as defined in claim 15, wherein said lipophilic substance further com¬ prises a biologically active lipophilic compound selected from the group consisting of prostaglandins, local anesthetic agents, proteins, peptides, antiviral agents, vitamins, antiinflammatory agents, antifungal agents, corticosteroids, plant extracts, a ino acids and nucleoside analogues. 22. A biphasic multilamellar lipid vesicle as defined in claim 21, wherein said biologically active lipophilic com- pound is selected from the group consisting of PGE- , tetra¬ caine, lidocaine, etidocaine, interferon alpha, interferon gamma, adenine-β-D-arabinofuranoside (Ara-A) , 5-methoxy- methyl-2'-deoxyuridine (MMTJdR) , vitamin A, vitamin C, vitamin E, provitamin B-., azulene, allantoin, alpha- bisabolol and L-carnitine. RECTIFIED SHEET (RULE 91) ISA/EP 23. A biphasic multilamellar lipid vesicle as defined in claim 12, wherein said lipophilic substance further in¬ cludes a biologically active lipophilic compound and said lipid bilayers have incorporated therein a biologically active agent. 24. A biphasic multilamellar lipid vesicle according to claim 12, wherein a biologically active substance is dis¬ solved in said water. 25. A liposome composition comprising biphasic multi- lamellar lipid vesicles, comprising: a plurality of spaced apart lipid bilayers comprising a liposome-forming component and optionally a biologically active agent entrapped within said lipid bilayers; and peripheral aqueous solution compartments formed between said lipid bilayers; and a central lipophilic core compartment substantially at the center of said multilamellar lipid vesicle. 26. A liposome composition according to claim 25, wherein said lipid bilayers further comprise a fatty substance adapted to enhance the strength of said lipid bilayers. 27. A liposome composition according to claim 25, wherein said lipid bilayers are formed from an anhydrous prolipo¬ some gel comprising said liposome-forming component in admixture with said fatty substance and a pharmaceutically acceptable hydrophilic solvent other than water. 28. A liposome composition according to claim 27, wherein said anhydrous proliposome gel further comprises a fatty substance adapted to enhance the strength of said lipid bilayers. RECTIFIED SHEET (RULE 91) ISA/EP 29. A liposome composition according to claim 25, wherein said liposome-forming component is selected from the group consisting of glycolipids, phospholipids, ceramides and mixtures thereof. 30. A liposome composition according to claim 26, wherein said fatty substance is cholesterol. 31. A liposome composition according to claim 25, wherein said lipid bilayers further comprise at least one cutaneous or percutaneous penetration enhancer agent entrapped within said lipid bilayers or absorbed on the surface thereof. 32. A liposome composition according to claim 31, wherein said penetration enhancer agent is a fatty acylated amino acid. 33. A liposome composition according to claim 31, wherein said penetration enhancer agent is monolauroyllysine or methyl salicylate. 34. A liposome composition according to claim 25, wherein said lipid bilayers have incorporated therein a prosta¬ glandin. 35. A liposome composition according to claim 34, wherein said prostaglandin is PGEl. 36. A liposome composition according to claim 25, wherein said central lipophilic core compartment comprises a lipo¬ philic substance-in-water emulsion in the form of at least one droplet comprising on its surface a liposome-formation promoting agent adapted to stabilize said liposome-forming component and to promote the formation of lipid vesicles around said droplet. RATIFIED SHEET (RULE 91) ISA/EP 37. A liposome composition according to claim 36, wherein said liposome-formation promoting agent is a surfactant. 38. A liposome composition according to claim 37, wherein said surfactant is a primary cationic emulsifier. 39. A liposome composition according to claim 38, wherein, wherein said primary cationic emulsifier is selected from the group consisting of cocamidopropyl PG-dimonium chloride phosphate, stearamido PG-dimonium chloride phosphate, lino- leamidopropyl PG-Dimonium chloride phosphate. 40. A liposome composition according to claim 36, wherein said lipophilic substance comprises at least one component selected from the group consisting of an oil and a solid or semisolid lipophilic consistency enhancer. 41. A liposome composition according to claim 40, wherein said oil is selected from the group consisting of olive oil, macadamia nut oil, rice bran oil, pumpkin seed oil, apricot kernel oil, hazelnut oil, rose hip seed oil, borage oil, tea tree oil, rocou oil, camellia oil, sweet almond oil, safflower oil, St. John's wort oil, lipodermol, pistachio nut oil, chia oil, kiwi seed oil, lesquerella oil, tiare oil, grapeseed oil, peanut oil, babassu oil, avocado oil, squalene, evening primrose oil, blackcurrent oil, pentaerythritol tetracaprylate/caprate, pentaerythri¬ tol tetraisostearate, cetearyl octanoate, canola oil, jojoba oil, peanut oil, rice bran oil, cottonseed oil, sunflower oil, corn oil, walnut oil, avocado oil, preu balsam, clove oil, eugenol, comfrey oily extract, german chamomile oily extract, cola nut oily extract, pot marigold oily extract, silver birch oily extract, cola nut oily extract, gingko biloba oily extract, witch hazel oily extract, willow oily extract, guarana oily extract, arnica oily extract, horse chestnut oily extract, eucalyptus oily RECTIFIED SHEET (RULE 91) ISA/EP extract, meadow sweet oily extract, rosemary oily extract, phyt'iod oily extract, coffee oily extract, mate oily extract, tea oily extract and ivy oily extract. 42. A liposome composition according to claim 40, wherein said solid or semisolid lipophilic consistency enhancer is selected from the group consisting of fatty alcohols, waxes, fatty alcohol fatty acid esters, glyceride esters, white petroleum and combinations thereof. 43. A multilamellar lipid vesicle according to claim 40, wherein said solid or semisolid lipophilic consistency enhancer is selected from the group consisting of beeswax, cetyl alcohol, stearyl alcohol, myristyl myristate, behenyl erucate, glyceryl stearate and cetyl palmitate. 44. A liposome composition according to claim 40, wherein said lipophilic substance further comprises a biologically active lipophilic compound. 45. A liposome composition according to claim 36, wherein a biologically active substance is dissolved in said water. 46. A liposome composition according to claim 25, wherein the diameter of said biphasic multilamellar lipid vesicles ranges from 0.2 to 20 μm. 47. A process for the preparation of biphasic multi¬ lamellar lipid vesicles having a plurality of lipid bilayers, said process comprising: - forming a lipid phase melt by mixing a liposome- forming component with a pharmaceutically acceptable hydrophilic solvent other than water and optionally a biologically active compound, to produce an anhydrous proliposome gel in the form of a stable liposome-forming lipid phase melt; RECTIFIED SHEET (RULE 91) ISA/EP adding to said proliposome gel a lipophilic substance in water emulsion optionally comprising a biologically active compound; and recovering said multilamellar lipid vesicles. 48. A process according to claim 47, wherein said solution is a lipophilic substance-in-water emulsion in the form of a plurality of droplets comprising on their surface a liposome-formation promoting agent adapted to stabilize said liposome-forming component and to promote the forma- tion of lipid vesicles around said droplets, said solution being prepared by dissolving said liposome-formation pro¬ moting agent in water and adding said lipophilic substance through said water. 49. A process according to claim 48, wherein said lipo- philic substance comprises at least one component selected from the group consisting of an oil and a solid or semi¬ solid lipophilic consistency enhancer. 50. A process according to claim 48, wherein said lipo¬ some-formation promoting agent is a surfactant. 51. A process according to claim 50, wherein said sur¬ factant is a primary cationic emulsifier. 52. A process according to claim 51, wherein said primary cationic emulsifier is selected from the group consisting of cocamidopropyl PG-dimonium chloride phosphate, stear- amido PG-dimonium chloride phosphate, linoleamidopropyl PG- Dimonium chloride phosphate. 53. A multilamellar lipid vesicle for topical application, said lipid vesicle comprising: RECTIFIED SHEET (RULE 91) ISA/EP a plurality of spaced apart lipid bilayers comprising a liposome-forming component and optionally a biologically active agent entrapped within said lipid bilayers; and peripheral aqueous solution compartments formed between said lipid bilayers and a central aqueous core compartment substantially at the center of said multi¬ lamellar lipid vesicle, said peripheral compartments comprising at least traces of a pharmaceutically acceptable hydrophilic solvent other than water, said multilamellar lipid vesicle being devoid of traces of organic solvents suitable for dissolving said lipid bilayers. 54. A multilamellar lipid vesicle according to claim 53, wherein said lipid bilayers have incorporated therein a prostaglandin. 55. A multilamellar lipid vesicle according to claim 54, wherein said protaglandin is PGE1. 56. A multilamellar lipid vesicle according to claim 53, wherein said lipid bilayers have incorporated therein interferon alpha. 57. A liposome composition comprising a population of multilamellar lipid vesicles, said multilamellar lipid vesicles comprising: a plurality of spaced apart lipid bilayers comprising a liposome-forming component and optionally a biologically active agent entrapped within said lipid bilayers; and peripheral aqueous solution compartments formed between said lipid bilayers and a central aqueous core compartment substantially at the center of said multi¬ lamellar lipid vesicle, said peripheral compartments co - prising at least traces of a pharmaceutically acceptable hydrophilic solvent other than water; **~-zg"-- n said multilamellar lipid vesicle population having a substantially uniform size distribution while being substantially devoid of aggregated or fused liposomes, and devoid of traces of organic solvents suitable for dissolving said lipid bilayers. 58. A process for the preparation of multilamellar lipid vesicles having a plurality of lipid bilayers, said process comprising: forming a lipid phase melt by mixing a liposome- forming component with a pharmaceutically acceptable hydrophilic solvent other than water and optionally a biologically active compound, to produce an anhydrous proliposome gel in the form of a stable liposome-forming lipid phase melt; - adding to said proliposome gel an aqueous solution optionally comprising a biologically active compound; and recovering said multilamellar lipid vesicles. 59. A composition for preparing multilamellar lipid vesicles having a plurality of lipid bilayers, said com- position comprising a liposome-forming component in admixture with a pharmaceutically acceptable hydrophilic solvent other than water to produce an anhydrous prolipo¬ some gel in the form of a stable liposome-forming lipid phase melt. 60. A method for the treatment of erectile dysfunctions, said method comprising topically administering to a patient in need thereof an effective amount of a liposome composi¬ tion comprising a population of multilamellar lipid vesicles, said multilamellar lipid vesicles comprising: - a plurality of spaced apart lipid bilayers comprising a liposome-forming component entrapped within said lipid bilayers; and RECTIFIED SHEET (RULE 91) ISA/EP peripheral aqueous solution compartments formed between said lipid bilayers and a central aqueous core compartment substantially at the center of said multi¬ lamellar lipid vesicle, said peripheral compartment comprising at least traces of a pharmaceutically acceptable hydrophilic solvent other than water; said multilamellar lipid vesicle population having a sub¬ stantially uniform size distribution while being substan¬ tially devoid of aggregated or fused liposomes and devoid of traces of organic solvents suitable for dissolving said lipid bilayers, for the purpose of treating impotence. 61. Use of a topical liposome composition for the applica¬ tion of PGE- in the treatment of erectile dysfunctions, said liposome composition comprising a population of multi- lamellar lipid vesicles, said lipid vesicles comprising: a plurality of spaced apart lipid bilayers comprising a liposome-forming component and PGE- entrapped within said lipid bilayers; and peripheral aqueous solution compartments formed between said lipid bilayers and a central aqueous core compartment substantially at the center of said multi¬ lamellar lipid vesicle, said peripheral compartment com¬ prising at least traces of a pharmaceutically acceptable hydrophilic solvent other than water; said multilamellar lipid vesicle population having a sub¬ stantially uniform size distribution while being substan¬ tially devoid of aggregated or fused liposomes and devoid of traces of organic solvents suitable for dissolving said lipid bilayers, for the purpose of treating erectile dys- functions. 62. Use of multilamellar lipid vesicles in the preparation of a topical medicament for the treatment of erectile dys¬ functions, said multilamellar lipid vesicles comprising: RECTIFIED SHEET (RULE 91) ISA/EP a plurality of spaced apart lipid bilayers comprising a liposome-forming component and PGE- entrapped within said lipid bilayers; and peripheral aqueous solution compartments formed between said lipid bilayers and a central aqueous core compartment substantially at the center of said multi¬ lamellar lipid vesicle, said peripheral compartment com¬ prising at least traces of a pharmaceutically acceptable hydrophilic solvent other than water; said multilamellar lipid vesicle population having a sub¬ stantially uniform size distribution while being substan¬ tially devoid of aggregated or fused liposomes and devoid of traces of organic solvents suitable for dissolving said lipid bilayers. 63. A method for the treatment of papillomavirus infec¬ tions, said method comprising topically administering to a patient in need thereof an effective amount of a liposome composition comprising a population of multilamellar lipid vesicles, said multilamellar lipid vesicles comprising: - a plurality of spaced apart lipid bilayers comprising a liposome-forming component and interferon alpha entrapped within said lipid bilayers; and peripheral aqueous solution compartments formed between said lipid bilayers and a central aqueous core compartment substantially at the center of said multi¬ lamellar lipid vesicle, said peripheral compartment com¬ prising at least traces of a pharmaceutically acceptable hydrophilic solvent other than water; said multilamellar lipid vesicle population having a sub- stantially uniform size distribution while being substan¬ tially devoid of aggregated or fused liposomes and devoid of traces of organic solvents suitable for dissolving said lipid bilayers, for the purpose of treating papillomavirus infections. RECTIFIED SHEET (RULE 91) ISA/EP 64. Use of a topical liposome composition for the application of interferon alpha in the treatment of papillomavirus infections, said liposome composition comprising a population of multilamellar lipid vesicles, said lipid vesicles comprising: a plurality of spaced apart lipid bilayers comprising a liposome-forming component and interferon alpha entrapped within said lipid bilayers; and peripheral aqueous solution compartments formed between said lipid bilayers and a central aqueous core compartment substantially at the center of said multi¬ lamellar lipid vesicle, said peripheral compartment com¬ prising at least traces of a pharmaceutically acceptable hydrophilic solvent other than water; said multilamellar lipid vesicle population having a substantially uniform size distribution while being sub¬ stantially devoid of aggregated or fused liposomes and devoid of traces of organic solvents suitable for dis¬ solving said lipid bilayers. 65. Use of multilamellar lipid vesicles in the preparation of a topical medicament for the treatment of papillomavirus infections, said multilamellar lipid vesicles comprising: a plurality of spaced apart lipid bilayers comprising a liposome-forming component and interferon alpha entrapped within said lipid bilayers; and peripheral aqueous solution compartments formed between said lipid bilayers and a central aqueous core compartment substantially at the center of said multi¬ lamellar lipid vesicle, said peripheral compartment com- prising at least traces of a pharmaceutically acceptable hydrophilic solvent other than water; said multilamellar lipid vesicle population having a substantially uniform size distribution while being sub¬ stantially devoid of aggregated or fused liposomes and RECTIFIED SHEET (RULE 91) ISA'EP devoid of traces of organic solvents suitable for dis¬ solving said lipid bilayers. RECTIFIED SHEET (RULE 91) ISA/EP

Inventors: FOLDVARI MARIANNA, FOLDVARI, MARIANNA
Applicants: FOLDVARI MARIANNA, UNIV SASKATCHEWAN, FOLDVARI, MARIANNA, UNIVERSITY OF SASKATCHEWAN
Application year: 1994
Main classification: A61K9
IPC codes: A61K8, A61K9, A61Q19